Exchange Biased Cofeb-Mgo Tunnel Junctions At The Onset Of Perpendicular Anisotropy With In-Plane/Out-Of-Plane Sensing Capabilities

We investigate the transport properties of exchange biased CoFeB-MgO tunnel junctions at the onset of perpendicular anisotropy of the CoFeB free layer. Angular dependent measurements of the tunnel conductance (varying the applied magnetic field from the in-plane to the out-of-plane direction) show linear and hysteresis-free switching under low applied magnetic fields, demonstrating a new concept for a reversible in-plane/out-of-plane magnetoresistive sensor. State-of-the-art sensitivities were achieved, and a value of 0.4% TMR/Oe is observed in the direction perpendicular to the tunnel junction plane. An analysis of the anisotropy energies at play is performed based on a Stoner-Wohlfarth like model. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3693585]